Signs posted within an environment play an important role in notifying onlookers of important information. Many signs merely serve to enhance the convenience of the public. For example, street signs are often used to inform pedestrians of their current location. However, other signs serve important public safety or regulatory functions. For example, some signs inform drivers of when it is legal to park their vehicle in a particular place. Other signs remind employees that they must wash their hands before returning to work after using the bathroom. Yet other signs warn people that wearing a hard hat is required to enter a construction site.
Although signs such as these play a significant role in informing and protecting the public, many signs consist of nothing more than a written warning, perhaps accompanied with some colored and/or flashing lights to get a passerby's attention. Getting people to notice these signs, read them, understand them, and comply with them can be a significant problem, particularly when such signs are used to warn the public of potentially life-threatening hazards nearby (e.g., high-voltage wires, minefields, heavy machinery, quarantine areas).